• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.786-789
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• 1989

A nonlinear self-tuning regulator for a neutralization process of a weak acid and strong base system is proposed. Rearranging the state equation of the process model, we first obtain equations which are linear for a manipulated variable or unknown parameters. Then to these equations we apply the standard procedure used in designing linear self-tuning regulators. Simulation results show that the regulator provides very good performances for various realistic situations and traces variations of the unknown parameters. Since computations are simple and additional measurements except the effluent pH value are only flow rates of influent streams, it can be easily applied to real processes such as a waste water treatment process.

• 대한기계학회논문집A
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• 제24권10호
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• pp.2535-2542
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• 2000

The regulator system has been modeled and combined to a swashplate type axial piston pump. Linear approximation has been performed for nonlinear coefficient terms of an axial piston pump-regulator model without significantly affecting accuracy. Based on the mathematical model of an axial piston pump-regulator system, a couple of characteristic curves of negative flow control and horsepower control are drawn, which show a good correlation with those of experimental results. So the simplified axial piston pump-regulator model in this paper is expected to be utilized not only for the design and analysis of hydraulic circuit of excavator but also for prevention of engine overload.

• International Journal of Precision Engineering and Manufacturing
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• 제1권1호
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• pp.79-83
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• 2000

Although it is well known that fuzzy learning controller is powerful for nonlinear systems, it is very difficult to apply a learning method if they are unstable. An unstable system diverges for impulse input. This divergence makes it difficult to learn the rules unless we can find the initial rules to make the system table prior to learning. Therefore, we introduced LQR(Linear Quadratic Regulator) technique to stabilize the system. It is a state feedback control to move unstable poles of a linear system to stable ones. But, if the system is nonlinear or complicated to get a liner model, we cannot expect good results with only LQR. In this paper, we propose that the LQR law is derived from a roughly approximated linear model, and next the fuzzy controller is tuned by the adaptive on-line learning with the real nonlinear plant. This hybrid controller of LQR and fuzzy learning was superior to the LQR of a linearized model in unstable nonlinear systems.

• 한국정밀공학회지
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• 제6권1호
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• pp.85-92
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• 1989

For feedback control of a linear dynamic system the optimum linear state regulator (OLSR) can be implemented only if all states are available for feedback. This work demonstrates that when only the output state is available for feedback, a nonlinear controllers can give improved performance over that obtained by a proportional controller. This paper found the optimal control law by dynamic programming and principles of optimalityl. This, performances of both proportional and nonlinear controllers are compared with performance of optimum linear state regulator.

• 조명전기설비학회논문지
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• 제23권11호
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• pp.69-75
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• 2009

In this paper, a self-tuning regulator for a speed control of a permanent magnet type stepping motor is proposed. The self-tuning theory provides a nonlinear modeling of a stepping motor drive system and can provide the controller with information regarding the reference variation and parameter variation of the stepping motor through the on-line estimation. The proposed self-tuning regulator organize the positive feedback loop and IP(Integral-Proportional) type. Therefore, the proposed self-tuning regulator has a robust control capabilities during dynamic operation. The availability of the proposed controller is verified through experimental results.

• 한국지능시스템학회논문지
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• 제12권6호
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• pp.554-558
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• 2002

In this paper, we propose a robust indirect adaptive fuzzy state feedback regulator based on Takagi-Sugeno fuzzy model. The proposed adaptive fuzzy regulator is less sensitive to singularity than the conventional one based on the feedback linearization method. Furthermore, the proposed control method is applicable to not only plants with a perfect model but also plants with an imperfect model, which causes uncertainties. We verify the global stability of the proposed method by using Lyapunov method. In order to support the achievement, the application of the proposed adaptive fuzzy regulator to the control of a nonlinear system under the external disturbance is presented and the performance was verified by some simulation result.

• 한국항공우주학회지
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• 제34권9호
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• pp.45-52
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• 2006

압전재료를 사용한 복합재료 패널의 플러터 억제 방법으로서 비선형 모델을 기반으로 하는 비선형 제어기법 중의 하나인 궤환 선형화에 의한 제어방법을 소개하였다. 기존의 패널 플러터 제어기에 대한 대부분의 연구들은 선형모델을 기반으로 설계된 선형2차제어기(LQR: Linear Quadratic Regulator)였음에 비해, 본 연구에서 제안한 비선형제어기는 시스템이 갖고 있는 비선형 특성들을 모두 고려해서 설계하였다. 압전 작동기로서는 PZT를 사용하였다. 가상변위의 원리와 4절점 사각형 요소를 사용하여 이산화된 비선형 운동방정식을 유도하였으며 제어기 설계를 위해 모달 변환을 통해 상태공간에서의 비선형 연계-모달 방정식으로 변환하였다. 본 논문에서 제안한 비선형 제어기에 의한 제어 결과와 선형모델을 기반으로 한 LQR 제어결과를 Newmark 수치적분법을 통해 시간영역에서 비교하였다.

• 한국자동차공학회논문집
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• 제14권6호
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• pp.160-170
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• 2006

If hydraulic pump controlled by mechanical type regulator has more than one control function, the construction of regulator will be very complicated and control performance falls drastically. It is difficult to have more than one control function for hydraulic pump controlled by electronic type hydraulic valve due to the inconsistency of controllers. This paper proposes a multi-function control technique which controls continuously flow, pressure and power by using EPPR(Electronic Proportional Pressure Reducing) valve in swash plate type axial piston pump. Nonlinear mathematical model is developed from the continuity equation for the pressurized control volume and the torque balance for the swash plate motion. To simplify the model we make the linear state equation by differentiating the nonlinear model. A reaction spring is installed in servo cylinder to secure the stability of the control system. We analyze the stability and disturbance by using the state variable model. Finally, we review the control performances of flow, pressure and power by tests using PID controller.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집(한일합동학술편); 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.812-816
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• 1987

A quadratic regulator problem for a class of nonlinear system, in which a small parameter multiplies the control cost, is considered. In the analysis of the problem, we utilize the method of multiple time-scale decomposition which has been devised for analyzing complex linear cheap control problems. In so doing, we extend the class of nonlinear systems, considerably, for which the minimum cost becomes zero as the small parameter goes to zero.

• 대한전기학회논문지
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• 제37권7호
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• pp.490-497
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• 1988

This paper is concerned with the robust stability of linear quadratic state feedback regulators for infinite dimensional systems in the presence of system uncertainties Several robustness results ensuring the asymptoitc stability and exponential stability of the perturbed closed loop system are derived for a class of nonlinear perturbations of the system and input operators satisfying the matching condition. For the case where the input space is finite dimensional, some robust properties of the state feedback regulator designed on the basis of the linear quadratic regulator for finite dimensional unstable modes are also discussed seperately.